リンパ節転移からみた直腸pm癌の治療方針

Policy of Treatment for pm Cancer of the Rectum According to Preoperative Diagnosis

要旨　最近ではリンパ節転移の術前診断が可能である．そこでリンパ節転移を含めた術前の所見から直腸pm癌の治療方針を検討した．自験直腸pm癌のうちリンパ節転移例の5年生存率は58.7％，肛門癌の5年生存率は75.8％，中分化腺癌の5年生存率は83.5％であり，これらは再発の危険因子と考えられた．一方これらの因子でないもの，すなわちリンパ節転移がなく，高分化腺癌で，RsとRaとRbの直腸pm癌の5年生存率は96.5％であるので，R₃でかつ自律神経温存手術の適応としてよい．この場合でも，Rbでは骨盤神経叢は温存して側方リンパ節を郭清する．リンパ節転移例，中分化腺癌，肛門部癌では自律神経を温存せずに側方リンパ節を郭清し，R₃の手術を行う．

　Recently, depth of invasion and lymph node metastasis of rectal cancer are diagnosed by CT, MRI and intrarectal ultrasonography before operation. According to the preoperative diagnosis, policy of treatment for intramuscular (pm) cancer of the rectum is discussed here.

　Five-year survival rate of pm cancer patients without lymph node metastasis located in the rectosigmoid, the upper rectum and the lower rectum whose pathological diagnosis are well-differentiated adenocarcinoma is 96.5%. This excellent result indicates that this group of pm cancer is suitable for autonomic nerve preserving operation in order to maintain the postoperative bladder function and the male sexual function.

　On the other hand, 5-year survival rates of pm cancer patients with lymph node metastasis, pm cancer whose pathological diagnosis is moderately-differentiated adenocarcinoma and pm cancer located in the anus are 58.7%, 75.8% and 83.5%, respectively. These groups of cancer are appropriate for extended radical resection of the rectum with lateral lymph node dissection.